Restrictive service period for power save devices

ABSTRACT

This disclosure describes systems, methods, and apparatus related to a restrictive target wake time (TWT) service period (SP) system. A device may determine a beacon frame to be sent to one or more power save devices. The device may determine a time duration of a TWT SP associated with the one or more power save devices. The device may determine a first trigger frame including a cascade indication. The device may determine a first time associated with the first trigger frame. The device may cause to send the trigger frame to the one or more power save devices based at least in part on a remaining duration of the TWT SP.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-provisional ApplicationNo. 15/197,293 filed Jun. 29, 2016, which claims the benefit of U.S.Provisional Application No. 62/275,171 filed Jan. 5, 2016, thedisclosures of which are incorporated herein by reference in theirentireties

TECHNICAL FIELD

This disclosure generally relates to systems and methods for wirelesscommunications and, more particularly, to a restrictive target wake time(TWT) service period (SP).

BACKGROUND

Wireless devices are becoming widely prevalent and are increasinglyrequesting access to wireless channels. A next generation WLAN, IEEE802.11ax or high-efficiency WLAN (HEW) utilizes orthogonalfrequency-division multiple access (OFDMA) in channel allocation. Beaconframes are management frames that contain information related totransmissions between devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a network diagram illustrating an example networkenvironment of a restrictive target wake time (TWT) service period (SP),in accordance with one or more example embodiments of the presentdisclosure.

FIG. 2 depicts an illustrative schematic diagram of a broadcast targetwake time (TWT) mechanism, in accordance with one or more exampleembodiments of the present disclosure.

FIG. 3 depicts an illustrative schematic diagram of a restrictive TWT SPsystem, in accordance with one or more example embodiments of thepresent disclosure.

FIG. 4A depicts a flow diagram of an illustrative process of arestrictive TWT SP system, in accordance with one or more exampleembodiments of the present disclosure.

FIG. 4B depicts a flow diagram of an illustrative process of arestrictive TWT SP system, in accordance with one or more exampleembodiments of the present disclosure.

FIG. 5 illustrates a functional diagram of an example communicationstation that may be suitable for use as a user device, in accordancewith one or more example embodiments of the present disclosure.

FIG. 6 illustrates a block diagram of an example machine upon which anyof one or more techniques (e.g., methods) may be performed, inaccordance with one or more example embodiments of the presentdisclosure.

DETAILED DESCRIPTION

Example embodiments described herein provide certain systems, methods,and devices for providing signaling to Wi-Fi devices in various Wi-Finetworks, including, but not limited to, IEEE 802.11ax (referred to asHE or HEW).

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

A design target for HEW is to adopt methods to improve the efficiency ofWi-Fi, and specifically the efficiency in dense deployments of Wi-Fidevices, such as in malls, conference halls, etc. HEW may use OFDMAtechniques for channel access in the uplink and downlink directions. Itis understood that the uplink direction is from a user device to anaccess point (AP), and the downlink direction is from an AP to one ormore user devices. In the uplink direction, one or more user devices maybe communicating with the AP and may be competing for channel access ina random channel access manner. In that case, the channel access inOFDMA may require coordination among the various user devices that maybe competing to access the operating channel simultaneously. A triggerframe may consist of a preamble along with other signaling, such asresource allocation, to coordinate the uplink OFDMA operation. A triggerframe may be a frame that contains a preamble and other fields that maybe sent from an AP informing all user devices serviced by the AP thatchannel access is available. A trigger frame may be sent in a mediumaccess control (MAC) layer or in a physical (PHY) layer.

In HEW, user devices may communicate with other user devices and/or APsin a scheduled or unscheduled (random) manner. In the scheduled manner,an AP may allocate and assign network resources to the user devices inorder to transmit their data. In the alternative, user devices mayrandomly access the operating channel to transmit their data. Utilizingthe trigger frame of HEW, the AP may send either a trigger frameindicating that one or more user devices are assigned scheduled resourceunits, or may send a random access trigger frame indicating that theresource units are available in a random access manner, where the userdevices randomly select one or more resource units. When a user devicedetects the trigger frame, it may use one of the one or more resourceunits associated with the trigger frame to send its uplink data. Inorder for an AP to notify the one or more user devices serviced by thatAP that a trigger frame is coming, the AP may send a beacon framespecifying the first scheduled trigger frame. It is understood that abeacon frame is one of the management frames in IEEE 802.11 basedwireless local area networks (WLANs). A beacon frame containsinformation about the network. Beacon frames may be transmittedperiodically to announce the presence of a WLAN. Beacon frames aretransmitted by the AP in an infrastructure basic service set (BSS).

An AP may send multiple trigger frames in one or more manners. The APmay schedule the trigger frames in an aperiodic cascaded sequence oftrigger frames, a periodic cascaded sequence of trigger frames, or arandom sequence of trigger frames. The aperiodic cascaded sequence oftrigger frames may be where the AP sends the trigger frames one afterthe other in sequence. The periodic cascaded sequence of trigger framesmay be where the AP sends the trigger frames at a specific timeinterval. The random sequence of trigger frames may be where the APsends the trigger frames randomly between a first time period and asecond time period. It is understood that the above descriptions are forpurposes of illustration and are not meant to be limiting.

Target wake time (TWT) is a function that permits an AP to define aspecific time or set of times for individual stations to access thetransmission medium. The user devices and the AP exchange informationthat includes an expected activity duration to allow the AP to controlthe amount of contention and overlap among competing user devices. Theuse of TWT may be negotiated between an AP and a user device or maybroadcasted by the AP to one or more user devices that may be associatedor unassociated with the AP. TWT may be used to reduce network energyconsumption, because user devices that use it can enter a doze stateuntil their TWT service period (SP) arrives. User devices wake up (poweron or become in an active state) during the allocated TWT SP and may bein a doze state (power off or become in an inactive state) outside ofthe TWT SP.

Power save (PS) devices may be devices such as an AP and/or user devicesalso may be referred to as stations (STAs). PS devices may utilize powersaving modes in order to increase the efficiency and flexibility of datatransmission. Specifically, the PS device may doze (go to an inactivestate or power off) between packets to save power, while the AP buffersdownlink frames that typically would have been sent to the PS device.The PS device and/or the AP determine the time when the PS device shouldwake up (go to an active state or power on) and receive data packets tomaximize power conservation without sacrificing quality of service(QoS).

An AP may schedule transmission of a trigger frame to one or more PSdevices during a TWT SP. The AP may set a bit (e.g., a cascadeindication (CI)) in a cascaded field of a trigger frame in order tonotify the one or more PS devices, whether additional trigger frameswill be sent or whether the received trigger frame is the last triggerframe within the TWT SP. With the cascaded field set to 1 (e.g., CI=1),the AP may transmit additional trigger frames for UL data reception fromthe same or different PS devices within the TWT SP. However, if thecascaded field is set to 0 in a trigger frame, the PS devices receivingthat trigger frame would be able to determine that the received triggerframe is the last trigger frame within the TWT SP. That is the triggerframe with a cascaded field set to 0 indicates the end of the triggerframe transmissions within the TWT SP.

However, there might be a potential issue with providing thisflexibility to the AP in scheduling multiple trigger frames using thecascaded field. The issue is in terms of extending the TWT SP, if acascaded trigger frame is scheduled very close to the end of the TWT SP.For example, the PS devices assigned resource units in a trigger framewill transmit UL PPDUs without taking into consideration the remainingduration of the TWT SP. However, PS devices that have set the networkallocation vector (NAV) based on the indicated TWT SP (either in abeacon or in the first trigger frame of the SP) will reset their NAVand, on gaining channel access, might potentially collide with the ULPPDUs of the PS devices. It is understood that NAV is a virtual carriersense, which is used by devices to reserve the medium for mandatoryframes, which must follow the current frame.

Example embodiments of the present disclosure relate to systems,methods, and devices for a restrictive TWT SP. Specifically for limitingthe allocation and transmission of trigger frames within a TWT SP inorder to minimize collisions between uplink (UL) frames or other frameswithin a TWT SP.

In one embodiment, a restrictive TWT SP system may prohibit an AP fromscheduling a trigger frame transmission close to the end of a TWT SP.

In another embodiment, a restrictive TWT SP system may set a cascadeindication field within a trigger frame to be sent to one or more PSdevices based at least in part on one or more conditions.

In another embodiment, a restrictive TWT SP system may determine one ormore conditions associated with the duration of the TWT SP such that thetrigger frame is sent to the one or more PS devices when the one or moreconditions are met. The one or more conditions may be associated withdetermining a remaining duration of the TWT SP and comparing that to oneor more durations associated with, at least in part, the trigger frame,one or more interframe space durations, one or more UL frame durations,and/or one or more acknowledgment durations.

In another embodiment, a restrictive TWT SP system may determine a lasttrigger frame to be sent to one or more PS devices based at least inpart on the cascade indication field being sent to a predeterminedvalue. For example, the AP may set the cascade indication field to 0 inthe last trigger frame within the TWT SP.

In one embodiment, a restrictive TWT SP system may determine anacknowledgment policy bit associated with the quality of service (QoS)field of an uplink frame. For example, if the acknowledgment policy bitis set to 1, this may indicate that the AP may receive an acknowledgmentfrom the one or more PS devices. However, if the acknowledgment policybit is set to 0, this may indicate that the AP will not be receiving anacknowledgment from the one or more PS devices. That is, somecommunications may automatically be determined to not requireacknowledgment, and some communications may be determined to always needacknowledgment. This may be based on, for example, a message type.

In one embodiment, a restrictive TWT SP system may ignore theacknowledgment policy bit based at least in part on the type ofcommunication between the AP and the one or more PS devices.

The above descriptions are for purposes of illustration and are notmeant to be limiting. Numerous other examples, configurations,processes, etc., may exist, some of which are described in detail below.Example embodiments will now be described with reference to theaccompanying figures.

FIG. 1 depicts a network diagram illustrating an example networkenvironment of a restrictive target wake time (TWT) service period (SP),in accordance with one or more example embodiments of the presentdisclosure. Wireless network 100 may include one or more user devices120 and one or more access point(s) (AP) 102, which may communicate inaccordance with IEEE 802.11 communication standards, including IEEE802.11ax. The user device(s) 120 may be mobile devices that arenon-stationary (e.g., not having fixed locations) or may be stationarydevices.

In some embodiments, the user devices 120 and the AP 102 may include oneor more computer systems similar to that of the functional diagram ofFIG. 5 and/or the example machine/system of FIG. 6.

One or more illustrative user device(s) 120 and/or AP 102 may beoperable by one or more user(s) 110. The user device(s) 120 (e.g., 124,126, or 128) and/or AP 102 may include any suitable processor-drivendevice including, but not limited to, a mobile device or a non-mobile,e.g., a static, device. For example, user device(s) 120 and/or AP 102may include, a user equipment (UE), a station (STA), an access point(AP), a personal computer (PC), a wearable wireless device (e.g.,bracelet, watch, glasses, ring, etc.), a desktop computer, a mobilecomputer, a laptop computer, an Ultrabook™ computer, a notebookcomputer, a tablet computer, a server computer, a handheld computer, ahandheld device, an internet of things (IoT) device, a sensor device, aPDA device, a handheld PDA device, an on-board device, an off-boarddevice, a hybrid device (e.g., combining cellular phone functionalitieswith PDA device functionalities), a consumer device, a vehicular device,a non-vehicular device, a mobile or portable device, a non-mobile ornon-portable device, a mobile phone, a cellular telephone, a PCS device,a PDA device which incorporates a wireless communication device, amobile or portable GPS device, a DVB device, a relatively smallcomputing device, a non-desktop computer, a “carry small live large”(CSLL) device, an ultra mobile device (UMD), an ultra mobile PC (UMPC),a mobile internet device (MID), an “origami” device or computing device,a device that supports dynamically composable computing (DCC), acontext-aware device, a video device, an audio device, an A/V device, aset-top-box (STB), a blu-ray disc (BD) player, a BD recorder, a digitalvideo disc (DVD) player, a high definition (HD) DVD player, a DVDrecorder, a HD DVD recorder, a personal video recorder (PVR), abroadcast HD receiver, a video source, an audio source, a video sink, anaudio sink, a stereo tuner, a broadcast radio receiver, a flat paneldisplay, a personal media player (PMP), a digital video camera (DVC), adigital audio player, a speaker, an audio receiver, an audio amplifier,a gaming device, a data source, a data sink, a digital still camera(DSC), a media player, a smartphone, a television, a music player, orthe like.

As used herein, the term “Internet of Things (IoT) device” is used torefer to any object (e.g., an appliance, a sensor, etc.) that has anaddressable interface (e.g., an Internet protocol (IP) address, aBluetooth identifier (ID), a near-field communication (NFC) ID, etc.)and can transmit information to one or more other devices over a wiredor wireless connection. An IoT device may have a passive communicationinterface, such as a quick response (QR) code, a radio-frequencyidentification (RFID) tag, an NFC tag, or the like, or an activecommunication interface, such as a modem, a transceiver, atransmitter-receiver, or the like. An IoT device can have a particularset of attributes (e.g., a device state or status, such as whether theIoT device is on or off, open or closed, idle or active, available fortask execution or busy, and so on, a cooling or heating function, anenvironmental monitoring or recording function, a light-emittingfunction, a sound-emitting function, etc.) that can be embedded inand/or controlled/monitored by a central processing unit (CPU),microprocessor, ASIC, or the like, and configured for connection to anIoT network such as a local ad-hoc network or the Internet. For example,IoT devices may include, but are not limited to, refrigerators,toasters, ovens, microwaves, freezers, dishwashers, dishes, hand tools,clothes washers, clothes dryers, furnaces, air conditioners,thermostats, televisions, light fixtures, vacuum cleaners, sprinklers,electricity meters, gas meters, etc., so long as the devices areequipped with an addressable communications interface for communicatingwith the IoT network. IoT devices may also include cell phones, desktopcomputers, laptop computers, tablet computers, personal digitalassistants (PDAs), etc. Accordingly, the IoT network may be comprised ofa combination of “legacy” Internet-accessible devices (e.g., laptop ordesktop computers, cell phones, etc.) in addition to devices that do nottypically have Internet-connectivity (e.g., dishwashers, etc.).

The user device(s) 120 and/or AP 102 may also include mesh stations in,for example, a mesh network, in accordance with one or more IEEE 802.11standards.

Any of the user device(s) 120 (e.g., user devices 124, 126, 128), and AP102 may be configured to communicate with each other via one or morecommunications networks 130 and/or 135 wirelessly or wired. Any of thecommunications networks 130 and/or 135 may include, but not limited to,any one of a combination of different types of suitable communicationsnetworks such as, for example, broadcasting networks, cable networks,public networks (e.g., the Internet), private networks, wirelessnetworks, cellular networks, or any other suitable private and/or publicnetworks. Further, any of the communications networks 130 and/or 135 mayhave any suitable communication range associated therewith and mayinclude, for example, global networks (e.g., the Internet), metropolitanarea networks (MANs), wide area networks (WANs), local area networks(LANs), or personal area networks (PANs). In addition, any of thecommunications networks 130 and/or 135 may include any type of mediumover which network traffic may be carried including, but not limited to,coaxial cable, twisted-pair wire, optical fiber, a hybrid fiber coaxial(HFC) medium, microwave terrestrial transceivers, radio frequencycommunication mediums, white space communication mediums, ultra-highfrequency communication mediums, satellite communication mediums, or anycombination thereof.

Any of the user device(s) 120 (e.g., user devices 124, 126, 128), and AP102 may include one or more communications antennas. The one or morecommunications antennas may be any suitable type of antennascorresponding to the communications protocols used by the user device(s)120 (e.g., user devices 124, 126 and 128), and AP 102. Some non-limitingexamples of suitable communications antennas include Wi-Fi antennas,Institute of Electrical and Electronics Engineers (IEEE) 802.11 familyof standards compatible antennas, directional antennas, non-directionalantennas, dipole antennas, folded dipole antennas, patch antennas,multiple-input multiple-output (MIMO) antennas, omnidirectionalantennas, quasi-omnidirectional antennas, or the like. The one or morecommunications antennas may be communicatively coupled to a radiocomponent to transmit and/or receive signals, such as communicationssignals to and/or from the user devices 120 and/or AP 102.

Any of the user device(s) 120 (e.g., user devices 124, 126, 128), and AP102 may be configured to perform directional transmission and/ordirectional reception in conjunction with wirelessly communicating in awireless network. Any of the user device(s) 120 (e.g., user devices 124,126, 128), and AP 102 may be configured to perform such directionaltransmission and/or reception using a set of multiple antenna arrays(e.g., DMG antenna arrays or the like). Each of the multiple antennaarrays may be used for transmission and/or reception in a particularrespective direction or range of directions. Any of the user device(s)120 (e.g., user devices 124, 126, 128), and AP 102 may be configured toperform any given directional transmission towards one or more definedtransmit sectors. Any of the user device(s) 120 (e.g., user devices 124,126, 128), and AP 102 may be configured to perform any given directionalreception from one or more defined receive sectors.

MIMO beamforming in a wireless network may be accomplished using RFbeamforming and/or digital beamforming. In some embodiments, inperforming a given MIMO transmission, user devices 120 and/or AP 102 maybe configured to use all or a subset of its one or more communicationsantennas to perform MIMO beamforming.

Any of the user devices 120 (e.g., user devices 124, 126, 128), and AP102 may include any suitable radio and/or transceiver for transmittingand/or receiving radio frequency (RF) signals in the bandwidth and/orchannels corresponding to the communications protocols utilized by anyof the user device(s) 120 and AP 102 to communicate with each other. Theradio components may include hardware and/or software to modulate and/ordemodulate communications signals according to pre-establishedtransmission protocols. The radio components may further have hardwareand/or software instructions to communicate via one or more Wi-Fi and/orWi-Fi direct protocols, as standardized by the Institute of Electricaland Electronics Engineers (IEEE) 802.11 standards. In certain exampleembodiments, the radio component, in cooperation with the communicationsantennas, may be configured to communicate via 2.4 GHz channels (e.g.802.11b, 802.11g, 802.11n, 802.11ax), 5 GHz channels (e.g. 802.11n,802.11ac, 802.11ax), or 60 GHZ channels (e.g. 802.11ad). In someembodiments, non-Wi-Fi protocols may be used for communications betweendevices, such as Bluetooth, dedicated short-range communication (DSRC),Ultra-High Frequency (UHF) (e.g. IEEE 802.11af, IEEE802.22), white bandfrequency (e.g., white spaces), or other packetized radiocommunications. The radio component may include any known receiver andbaseband suitable for communicating via the communications protocols.The radio component may further include a low noise amplifier (LNA),additional signal amplifiers, an analog-to-digital (A/D) converter, oneor more buffers, and digital baseband.

When an AP (e.g., AP 102) establishes communication with one or moreuser devices 120 (e.g., user devices 124, 126, and/or 128), the AP 102may communicate in a downlink direction and the user devices 120 maycommunicate with the AP 102 in an uplink direction by sending dataframes in either direction. The data frames may be preceded by one ormore preambles that may be part of one or more headers. These preamblesmay be used to allow a device (e.g., AP 102 and/or user devices 120) todetect a new incoming data frame from another device. A preamble may bea signal used in network communications to synchronize transmissiontiming between two or more devices (e.g., between the APs and the userdevices).

During a communication between the AP 102 and one or more user devices120, which may be PS devices, an AP may have already determined to senda beacon frame 104 to the one or more user devices 120 (e.g., userdevices 124, 126, and/or 128). The beacon frame 104 may be used in orderfor an AP 102 to notify the one or more user devices 120 serviced bythat AP 102 that a trigger frame may be transmitted, and the AP 102 maysend a beacon frame 104 specifying one or more types of informationincluded, at least in part in one or more information elements (IEs).For example, a target wake time (TWT) IE may be associated with aservice period (SP), where the SP is a period of time that the one ormore user devices 120 could come out of the doze state, that is when theone or more user devices 120 may wake up or power on or go into anactive state, if needed. The beacon frame 104 may notify the one or moreuser devices 120, among other things, about when the SP starts (e.g., attime T1). The beacon frame 104 may also notify the one or more userdevices 120 when, if any, trigger frame 108 will be sent out to the oneor more user devices 120. The trigger frame 108 may also be utilized topoll the one or more user devices 120 to determine whether they have ULtransmissions. The one or more user devices 120 may send their ULtransmissions if they have any. After that, the AP 102 may respond tothe one or more user devices 120 that send their UL transmissions bysending an acknowledgment (e.g., ACK 114). The acknowledgment may be asingle ACK to each of the user devices 120 that sent UL transmissions,may be a block ACK, or may be a multi-user block ACK (MBA).

FIG. 2 depicts an illustrative schematic diagram of a broadcast targetwake time (TWT) mechanism, in accordance with one or more exampleembodiments of the present disclosure.

With reference to FIG. 2, the AP 202 and a user device 234 may begin thenegotiation through an optional target beacon transmission time (TBTT)211, where the TBTT 211 indicates when a beacon (e.g., beacon 214) maybe sent by the AP 202. For example, the user device 234 may send a TWTrequest 210 and the AP 202 may reply with a TWT response 212. The TWTperiod may be established using negotiated TWT or broadcasted TWTmechanisms. A negotiated TWT mechanism may be negotiated between one ormore user devices 120 (e.g., user devices 234 and 236) and an AP (e.g.,AP 202), also referred to as an implicit TWT mechanism. A broadcastedTWT mechanism may be indicated by the AP 202 in a TWT informationelement (IE) indicated in a beacon 214. The beacon 214 may be sent aftera channel access (e.g., channel access 213) after the TBTT 211.

After the optional TBTT negotiation, the user device 234, whichinitiated the TBTT negotiation, may enter into a doze state until afterthe target beacon transmission time TBTT 211. A doze state is understoodto indicate that a PS device may enter a sleep mode or power off or gointo an inactive state, if needed. As can be seen in FIG. 2, the userdevice 234 remains in a doze state after TBTT 211, after beacon 214,after TWT SP 216, after the unannounced TWT SP, etc. When the userdevice 234 is not in a doze state, the user device 234 may be in anawake state, powered on, or in an active state such that the user device234 is capable of communicating and/or listening to communications with,at least in part, the AP 202 or one or more other PS devices.

FIG. 2 shows a negotiated TWT mechanism, where the AP 202 indicates thetarget trigger times for trigger frame transmissions in the beacon 214.Additionally, the AP 202 may indicate in the beacon 214 a target time(e.g., T1) as a start time of a TWT service period (SP) 216. Within theTWT SP 216, the AP 202 may transmit a trigger frame 218 to pollmulti-user (MU) uplink (UL) transmissions from multiple PS user devices(e.g., user devices 234 and 236). In that case, the PS devices may senda PS poll frame (e.g., PS-Poll frame 230). In one example, the PS-Pollframe 230 may be used to inform the AP 202 of any uplink data that theuser device may have. Following the UL transmissions that may betransmitted from one or more of the PS user devices, the AP 202 may senda multi-user block acknowledgment (BA) frame 220 acknowledging the ULtransmissions received by the AP 202.

Moreover, the trigger frame 218 may be one of one or more cascadedtrigger frames that may be sent by the AP 202 during the TWT SP 216. Forexample, the AP 202 may set a trigger field to 1 to indicate atrigger-enabled TWT. That is, one or more trigger frames may be sent bythe AP. Otherwise, that AP 202 may set the trigger field to 0 toindicate a non-trigger enabled TWT. That is, only one trigger frame issent by the AP. The AP 202 may schedule the transmission of one or moretrigger frames intended for one or more PS devices (e.g., 234 and 236)during a trigger-enabled TWT SP (e.g. TWT SP 216). The AP 202 may intendto transmit additional trigger frames during a trigger-enabled TWT SP bysetting a cascaded field included in the trigger frame 218 to 1 toindicate that it will transmit another trigger frame within the same TWTSP 216. Otherwise, the AP 202 may set the cascaded field to 0 toindicate the end of the trigger frame transmission and that the triggerframe containing the cascaded field having a value of 0 is the lasttrigger frame in the TWT SP 216.

However, with the cascaded field set to 1, the AP 202 may transmitmultiple cascaded trigger frames for UL data reception from the same orfrom different SP devices within the trigger-enabled TWT SP (e.g., TWTSP 216). There may be problems with providing this flexibility to the APin scheduling multiple trigger frames using the cascaded indication.Problems may arise, for example, when a trigger frame is scheduled fortransmission close to the end of the TWT SP 216 (e.g., close to T2). ThePS devices (e.g., user devices 234 and 236) assigned resource units(RUs) in this trigger frame may then transmit UL PLCP Protocol DataUnits (PPDUs) after a short interframe space (SIFS). However, the PSdevices that have set a network allocation vector (NAV) based on theindicated TWT SP (e.g. either in a beacon or in the first trigger frameof the SP) can reset their NAVs. After gaining channel access, they maycollide with the UL PPDUs of other PS devices.

FIG. 2 also shows a scenario where an unannounced TWT SP may bescheduled by the AP 202 at time T3 and where the unannounced TWT SP endsat T4. In that case, the AP 202 may send, after a channel access delay217, a downlink (DL) MU PPDU, which may be sent to the one or more PSdevices (e.g., user devices 234 and/or 236) to communicate with thesedevices. A similar issue also occurs in the unannounced TWT SP where theone or more user devices may send their UL PPDU transmissions close tothe end of the unannounced TWT SP. It is understood that the abovedescriptions are for purposes of illustration and are not meant to belimiting.

FIG. 3 depicts an illustrative schematic diagram of a restrictive TWT SPsystem, in accordance with one or more example embodiments of thepresent disclosure.

Referring to FIG. 3, there is shown an AP 302 that may be communicatingwith a PS device (e.g., user device 340). The AP 302 may send a beacon310 to the user device 340. The beacon 310 may indicate, in thisexample, a first trigger frame 312 that may be sent at time T1. Thetrigger frame 312 may be sent to at least the user device 340. After achannel access delay 311, the beacon 310 may contain a TWT IE that maybe utilized to indicate the type of TWT mechanism (e.g., broadcasted ornegotiated TWT mechanism) to be used and/or the trigger frame 312transmission time (e.g., T1), among other possible information relatedto the one or more trigger frames.

As depicted in FIG. 3, if the AP 302 determines that cascaded triggerframes will be sent to the user devices (e.g., user device 340), the AP302 may set the cascade indication (CI) field to 1 in the trigger frame312. When the user device 340 receives the trigger frame 312, the userdevice 340 may decode the trigger frame 312 and extract the cascadeindication, which, in this example, is equal to 1. The user device 340may determine that additional trigger frames may be sent by the AP 302based on that cascade indication. The AP 302 may schedule a next triggerframe 316 in one or more cascaded trigger frames. If the trigger frame316 is the last trigger frame in the cascaded trigger frames, the AP 302may set the cascade indication to 0 in the trigger frame 316 in order toindicate that it is the last trigger frame within the TWT SP 314. TheTWT SP 314 may have a starting time (e.g., T1) and an end time (e.g.,T2). Each trigger frame may possibly trigger a response from the userdevice (e.g., user device 340) receiving the trigger frame. Therefore,in at least one embodiment of the present disclosure, the AP 302 maydetermine the remaining duration of the TWT SP 314 before scheduling anext trigger frame in order to ensure there is enough time to send thelast trigger frame, and receive expected responses from the user devicebefore the expiration of the TWT SP 314.

A cascaded trigger frame (e.g., trigger frame 316) may be sent by the AP302 close to the end of the duration of the TWT SP 314 (e.g., close toT2). This may occur even though there may not be enough time for UL MUPPDU transmissions and acknowledge/block acknowledgment (ACK/BA)transmissions within the allocated TWT SP 314. If TWT SP 314 is extendedbeyond the interval indicated in the TWT IE, the user devices (e.g.,user device 340) that do not access the channel within the TWT SP 314may reset their respective NAVs. The chances of collision are therebyincreased due to the hidden terminal problem of user devices involved inUL MU PPDUs and user devices attempting channel access throughcontention. Hence, the TWT SP 314 may not be extended beyond theindicated TWT SP.

In one embodiment, an AP (e.g., AP 302) may be prohibited fromscheduling a trigger frame (e.g., trigger frame 316) close to the end ofthe TWT SP (e.g., close to T2). That is, an AP may refrain from sendinga trigger frame, if the trigger frame is within a certain threshold fromthe end of the TWT SP. For example, in the case of cascaded triggerframes where one or more trigger frames (e.g., trigger frames 312 and316) may be sent by the AP to one or more user devices (e.g., userdevice 340), the AP may set the cascade indication bit to 1 in the firsttrigger frame (e.g., trigger frame 312) in order to indicate to the userdevices that other trigger frames may also be transmitted. However, ifthe AP determines that another trigger frame (e.g., trigger frame 316)in the cascaded trigger frames will be sent within a threshold time fromthe end time of the TWT SP, the AP may refrain from sending that triggerframe and may set the cascade indication to 0 in the current triggerframe before sending it to the user devices.

In one embodiment, the AP (e.g., a high efficiency (HE) AP such as AP302) may set the cascade indication field to “1” in a current triggerframe if a predetermined condition is satisfied. That is, if the AP 302determines that there is enough time to send the last trigger frame(e.g., trigger frame 316) and still be able to send and receive expectedframes during the TWT SP 314.

In one embodiment, the AP may determine acknowledgment policy settingsbefore setting the cascade indication in a trigger frame of the cascadedtrigger frames. For example, the AP may determine the value of the ACKpolicy subfield within a QoS control field in the UL PPDU. That is, theAP 302 may determine if a value in the ACK policy subfield has been setto a value to indicate an immediate ACK/BA (to indicate that an ACK/BAmay be expected from at least one of the user devices) within the QoScontrol field in the UL PPDUs before determining whether to set thecascade indication in the trigger frame. For example, the value may be“01,” or any other value. In a case where the ACK policy subfield is setto immediate ACK/BA, the predetermined condition must be satisfiedbefore setting the cascade indication to 1. It should be understood thatthere are UL or DL transmissions and an ACK prior to the transmission ofthe second (cascaded) trigger frame (e.g., trigger frame 316). In otherwords, trigger frame 316 may not be transmitted after another triggerframe (e.g., trigger frame 312) unless the predetermined condition issatisfied. After the trigger frame 312, in a UL MU operation the userdevices may send their UL data to the AP, followed by a multi-user BA(MBA) from the AP. The predetermined condition takes into account the ULdata and the MBA durations before sending the trigger frame 316.

In a DL MU operation (e.g., AP sending data to user devices), thetrigger frame 312 may be aggregated with MU DL data for multiple userdevices, followed by UL MU ACK from the user devices. The predeterminedcondition takes into account these durations before sending the triggerframe 316.

After such an UL or DL MU operation, the second (cascaded) trigger frame316 may be transmitted by the AP. Therefore, the remaining time may becomputed from the end of the ACK transmission (in either UL or DL MUoperation) (e.g., time T3) to the end of the TWT SP (e.g., time T2).

The predetermined condition may be that the remaining duration of thetrigger-enabled TWT SP be greater than or equal to the sum of thecascaded trigger frame (e.g., trigger frame 316) duration, the SIFS(e.g., SIFS 313), the UL or DL PPDU length, an additional SIFS, and theACK/BA(e.g., duration 318). In this case, the predetermined conditionaccounts for expected frames that may be sent and/or received by the APduring the TWT SP 314. For example, the predetermined condition takesinto consideration channel access times, such as SIFS, before each frameto be sent by the AP, and takes into consideration the duration of theframes (e.g., trigger frame 316, UL or DL PPDU, ACK/BA/MBA, etc.). Thisprovides an enhanced TWT SP such that collisions are minimized, in caseframes are received outside the TWT SP.

In another embodiment, if the ACK policy subfield is set to 00(indicating no immediate ACK/BA), the AP 302 may determine whether toset the cascade indication to 1, if the remaining duration of TWT SP 314is greater than or equal to the sum of the cascaded trigger frame (e.g.,trigger frame 316) duration, the SIFS duration, and the UL PPDU length.It should be understood that although the value 00 is chosen to indicateno immediate ACK/BA, it is only for illustrative purposes and othervalues may be selected to indicate no immediate ACK/BA. In thealternative, if the AP 302 determines that the remaining duration of theTWT SP 314 is less than the sum of the trigger frame 316 duration, theSIFS duration and the UL PPDU duration, the AP 302 may set the cascadeindication to 0.

In another embodiment, the AP (e.g., a high efficiency (HE) AP) may setthe cascade indication bit to 0 in the last trigger frame within the TWTSP 314. That is, when the AP is done sending trigger frames in a seriesof cascaded trigger frames within the TWT SP 314, the AP may set thelast trigger frame to have a cascade indication bit of 0, informing theuser devices receiving the trigger frames from the AP 302 that this isthe last trigger frame.

In another embodiment, if the ACK policy bit is ignored, such that ULPPDUs are always acknowledged by sending acknowledgments (e.g.,ACK/BA/MBA), the AP may set the cascade indication bit to 1 in a currenttrigger frame if the following condition is satisfied: the remainingduration of the trigger-enabled TWT SP is greater than or equal to thesum of the cascaded trigger frame duration (e.g., trigger frame 316),the SIFS, the UL PPDU length, and the ACK/BA. For example, if the APdetermines that the remaining duration 320 is greater than the sum ofthe duration of the expected frames that may be allocated and/orreceived within the TWT SP 314, the AP may refrain from sending thetrigger frame.

FIG. 4A illustrates a flow diagram of an illustrative process 400 for anillustrative restrictive TWT SP system, in accordance with one or moreexample embodiments of the present disclosure.

At block 402, a device (e.g., the user device(s) 120 and/or the AP 102of FIG. 1) may determine a beacon frame to be sent to one or more powersave devices (e.g., user device(s) 120). As explained above, the TWT maybe established using either a negotiated TWT mechanism or a broadcastedTWT mechanism. In the negotiated TWT mechanism, for example, an optionalTBTT negotiation between the AP and one or more user devices may beperformed in order to determine the details of a TWT SP such that theone or more user devices are able to send and receive transmissions andenter into a doze state or inactive state. During the optional TBTTnegotiation, a user device may send a TWT request to the AP, and the APmay respond with a TWT response. The TWT response may containinformation of a target time for the transmission of a first beacon fromthe AP. The beacon may contain information associated with a timeduration for when the user device should wake up in order to transmitframes to the AP.

At block 404, the device may determine a time duration of a target waketime (TWT) service period (SP) associated with the one or more powersave devices (e.g., user device(s) 120). The beacon may contain, but isnot limited to, the duration of the TWT SP, the beginning time of theTWT SP, and the end time of the TWT SP. The user device may decode thebeacon and/or extract this information in order to determine when totransmit one or more of its uplink frames, such as UL PPDU and/oracknowledgments.

At block 406, the device may determine a first trigger frame including acascade indication. For example, the AP may set a cascade indication toeither a 1 or a 0 based at least in part on whether additional triggerframes will be sent to the one or more user devices. If the APdetermines that an additional trigger frame will be sent, the AP may setthe cascade indication in the first trigger frame to 1. However, if theAP determines that only one trigger frame is to be sent, the AP may setthe cascade indication to 0. In the same sense, the AP may set thecascade indication to 0 in the trigger frame to be sent as the lasttrigger frame within the TWT SP.

At block 408, the device may determine a first time associated with thefirst trigger frame. For example, the AP may determine the time when thefirst trigger frame will be sent to the one or more user devices. The APmay use that determination in order to send the trigger frame at thattime. The user device may then receive the trigger frame, and maydetermine whether additional trigger frames are expected based at leastin part on determining the value of the cascade indication that is setin the received trigger frame.

At block 410, the device may cause to send the trigger frame to the oneor more power save devices based at least in part on a remainingduration of the TWT SP. For example, the AP may determine whether tosend a trigger frame based at least in part on the remaining duration ofthe TWT SP. The AP may be prohibited from scheduling a trigger frameclose to the end of the TWT SP. That is, an AP may refrain from sendinga trigger frame, if the trigger frame is within a certain threshold fromthe end of the TWT SP.

The AP may set the cascade indication field to “1” in a current triggerframe indicating a transmission of an additional trigger frame after thecurrent trigger frame may be expected, if a predetermined condition issatisfied. That is, if the AP determines that there is enough time tosend the last trigger frame and still be able to send and receiveexpected frames during the TWT SP 314.

The AP may determine an acknowledgment policy setting before setting thecascade indication in a trigger frame of the cascaded trigger frames.For example, the AP may determine the value of the ACK policy subfieldwithin a QoS control field in the UL PPDU. That is, the AP may determineif a value in the ACK policy subfield has been set to “01” beforedetermining whether to set the cascade indication in the trigger frame.In the case where the ACK policy subfield is set to 01, thepredetermined condition that must be satisfied before setting thecascade indication to 1 may be that the remaining duration of thetrigger-enabled TWT SP be greater than or equal to the sum of thecascaded trigger frame duration, the SIFS, the UL PPDU length, anadditional SIFS, and the ACK/BA. In this case, the predeterminedcondition accounts for expected frames that may be sent and/or receivedby the AP during the TWT SP. This provides an enhanced TWT SP such thatcollisions are minimized, in case frames are received outside the TWTSP.

If the ACK policy subfield is set to 00 (indicating no immediateACK/BA), the AP may determine whether to set the cascade indication to1, if the remaining duration of the TWT SP is greater than or equal tothe sum of the cascaded trigger frame duration, the SIFS duration, andthe UL PPDU length. It should be understood that although the value 00is chosen to indicate no immediate ACK/BA, it is only for illustrativepurposes and other values may be selected to indicate no immediateACK/BA. In the alternative, if the AP determines that the remainingduration of the TWT SP is less than the sum of the trigger frame 316duration, the SIFS duration and the UL PPDU duration, the AP 302 may setthe cascade indication to 0 indicating that the current trigger frame isthe last trigger frame within the TWT SP.

If the ACK policy bit is ignored, such that UL PPDUs are alwaysacknowledged by sending acknowledgments (e.g., ACK/BA/MBA), the AP mayset the cascade indication bit to 1 in a current trigger frame if thefollowing condition is satisfied: the remaining duration of thetrigger-enabled TWT SP is greater than or equal to the sum of thecascaded trigger frame duration, the SIFS, the UL PPDU length, anadditional SIFS, and the ACK/BA. For example, if the AP determines thatthe remaining duration is greater than the sum of the duration ofexpected frames that may be allocated and/or received within the TWT SP,the AP may refrain from sending the trigger frame. It is understood thatthe above descriptions are for purposes of illustration and are notmeant to be limiting.

FIG. 4B illustrates a flow diagram of an illustrative process 450 for anillustrative restrictive TWT SP system, in accordance with one or moreexample embodiments of the present disclosure.

At block 452, a device (e.g., the user device(s) 120 and/or the AP 102of FIG. 1) may identify a beacon received from a first device (e.g., anAP). For example, a user device (e.g., a power device) may receive thebeacon from an AP. The user device may decode and/or extract informationfrom the received beacon. For example, the information may be associatedwith a time duration for when the user device should wake up in order totransmit frames to the AP.

At block 454, the device may determine a target wake time (TWT) serviceperiod (SP). For example, the user device may extract the TWT SP inorder to determine a beginning time and an end time of the TWT SP. Thisinformation allows the user device to determine when to wake up (poweron) in order to transmit one or more frames, such as UL PPDU andacknowledgment frames.

At block 456, the device may identify a trigger frame including acascade indication based at least in part on a remaining duration of theTWT SP. For example, the AP may have included information in the beaconon when the first trigger frame should be expected by the user device.The user device may be in an inactive mode until that time. The userdevice may then go into an active mode in order to receive and identifythe first trigger frame. This trigger frame may include additionalinformation such as a cascade indication bit. The user device mayextract the cascade indication to determine whether additional triggerframes should be expected. For example, if the cascade indication wasdetermined to be equal to 0, then the user device may determine thatthis trigger frame is the last trigger frame. However, if the userdevice determines that the cascade indication was equal to 1, then theuser device may determine that, at a minimum, an additional triggerframe may be expected. It is understood that the above descriptions arefor purposes of illustration and are not meant to be limiting.

FIG. 5 shows a functional diagram of an exemplary communication station500 in accordance with some embodiments. In one embodiment, FIG. 5illustrates a functional block diagram of a communication station thatmay be suitable for use as an AP 102 (FIG. 1) or user device 120(FIG. 1) in accordance with some embodiments. The communication station500 may also be suitable for use as a handheld device, a mobile device,a cellular telephone, a smartphone, a tablet, a netbook, a wirelessterminal, a laptop computer, a wearable computer device, a femtocell, ahigh data rate (HDR) subscriber station, an access point, an accessterminal, or other personal communication system (PCS) device.

The communication station 500 may include communications circuitry 502and a transceiver 510 for transmitting and receiving signals to and fromother communication stations using one or more antennas 501. Thecommunications circuitry 502 may include circuitry that can operate thephysical layer (PHY) communications and/or media access control (MAC)communications for controlling access to the wireless medium, and/or anyother communications layers for transmitting and receiving signals. Thecommunication station 500 may also include processing circuitry 506 andmemory 508 arranged to perform the operations described herein. In someembodiments, the communications circuitry 502 and the processingcircuitry 506 may be configured to perform operations detailed in FIGS.2-4.

In accordance with some embodiments, the communications circuitry 502may be arranged to contend for a wireless medium and configure frames orpackets for communicating over the wireless medium. The communicationscircuitry 502 may be arranged to transmit and receive signals. Thecommunications circuitry 502 may also include circuitry formodulation/demodulation, upconversion/downconversion, filtering,amplification, etc. In some embodiments, the processing circuitry 506 ofthe communication station 500 may include one or more processors. Inother embodiments, two or more antennas 501 may be coupled to thecommunications circuitry 502 arranged for sending and receiving signals.The memory 508 may store information for configuring the processingcircuitry 506 to perform operations for configuring and transmittingmessage frames and performing the various operations described herein.The memory 508 may include any type of memory, including non-transitorymemory, for storing information in a form readable by a machine (e.g., acomputer). For example, the memory 508 may include a computer-readablestorage device, read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memory devicesand other storage devices and media.

In some embodiments, the communication station 500 may be part of aportable wireless communication device, such as a personal digitalassistant (PDA), a laptop or portable computer with wirelesscommunication capability, a web tablet, a wireless telephone, asmartphone, a wireless headset, a pager, an instant messaging device, adigital camera, an access point, a television, a medical device (e.g., aheart rate monitor, a blood pressure monitor, etc.), a wearable computerdevice, or another device that may receive and/or transmit informationwirelessly.

In some embodiments, the communication station 500 may include one ormore antennas 501. The antennas 501 may include one or more directionalor omnidirectional antennas, including, for example, dipole antennas,monopole antennas, patch antennas, loop antennas, microstrip antennas,or other types of antennas suitable for transmission of RF signals. Insome embodiments, instead of two or more antennas, a single antenna withmultiple apertures may be used. In these embodiments, each aperture maybe considered a separate antenna. In some multiple-input multiple-output(MIMO) embodiments, the antennas may be effectively separated forspatial diversity and the different channel characteristics that mayresult between each of the antennas and the antennas of a transmittingstation.

In some embodiments, the communication station 500 may include one ormore of a keyboard, a display, a non-volatile memory port, multipleantennas, a graphics processor, an application processor, speakers, andother mobile device elements. The display may be an LCD screen includinga touch screen.

Although the communication station 500 is illustrated as having severalseparate functional elements, two or more of the functional elements maybe combined and may be implemented by combinations ofsoftware-configured elements, such as processing elements includingdigital signal processors (DSPs), and/or other hardware elements. Forexample, some elements may include one or more microprocessors, DSPs,field-programmable gate arrays (FPGAs), application specific integratedcircuits (ASICs), radio-frequency integrated circuits (RFICs) andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements of the communication station 500 may refer to one ormore processes operating on one or more processing elements.

Certain embodiments may be implemented in one or a combination ofhardware, firmware, and software. Other embodiments may also beimplemented as instructions stored on a computer-readable storagedevice, which may be read and executed by at least one processor toperform the operations described herein. A computer-readable storagedevice may include any non-transitory memory mechanism for storinginformation in a form readable by a machine (e.g., a computer). Forexample, a computer-readable storage device may include read-only memory(ROM), random-access memory (RAM), magnetic disk storage media, opticalstorage media, flash-memory devices, and other storage devices andmedia. In some embodiments, the communication station 500 may includeone or more processors and may be configured with instructions stored ona computer-readable storage device memory.

FIG. 6 illustrates a block diagram of an example of a machine 600 orsystem upon which any one or more of the techniques (e.g.,methodologies) discussed herein may be performed. In other embodiments,the machine 600 may operate as a standalone device or may be connected(e.g., networked) to other machines. In a networked deployment, themachine 600 may operate in the capacity of a server machine, a clientmachine, or both in server-client network environments. In an example,the machine 600 may act as a peer machine in peer-to-peer (P2P) (orother distributed) network environments. The machine 600 may be apersonal computer (PC), a tablet PC, a set-top box (STB), a personaldigital assistant (PDA), a mobile telephone, a wearable computer device,a web appliance, a network router, a switch or bridge, or any machinecapable of executing instructions (sequential or otherwise) that specifyactions to be taken by that machine, such as a base station. Further,while only a single machine is illustrated, the term “machine” shallalso be taken to include any collection of machines that individually orjointly execute a set (or multiple sets) of instructions to perform anyone or more of the methodologies discussed herein, such as cloudcomputing, software as a service (SaaS), or other computer clusterconfigurations.

Examples, as described herein, may include or may operate on logic or anumber of components, modules, or mechanisms. Modules are tangibleentities (e.g., hardware) capable of performing specified operationswhen operating. A module includes hardware. In an example, the hardwaremay be specifically configured to carry out a specific operation (e.g.,hardwired). In another example, the hardware may include configurableexecution units (e.g., transistors, circuits, etc.) and a computerreadable medium containing instructions where the instructions configurethe execution units to carry out a specific operation when in operation.The configuring may occur under the direction of the executions units ora loading mechanism. Accordingly, the execution units arecommunicatively coupled to the computer-readable medium when the deviceis operating. In this example, the execution units may be a member ofmore than one module. For example, under operation, the execution unitsmay be configured by a first set of instructions to implement a firstmodule at one point in time and reconfigured by a second set ofinstructions to implement a second module at a second point in time.

The machine (e.g., computer system) 600 may include a hardware processor602 (e.g., a central processing unit (CPU), a graphics processing unit(GPU), a hardware processor core, or any combination thereof), a mainmemory 604 and a static memory 606, some or all of which may communicatewith each other via an interlink (e.g., bus) 608. The machine 600 mayfurther include a power management device 632, a graphics display device610, an alphanumeric input device 612 (e.g., a keyboard), and a userinterface (UI) navigation device 614 (e.g., a mouse). In an example, thegraphics display device 610, alphanumeric input device 612, and UInavigation device 614 may be a touch screen display. The machine 600 mayadditionally include a storage device (i.e., drive unit) 616, a signalgeneration device 618 (e.g., a speaker), a restrictive TWT SP device619, a network interface device/transceiver 620 coupled to antenna(s)630, and one or more sensors 628, such as a global positioning system(GPS) sensor, a compass, an accelerometer, or other sensor. The machine600 may include an output controller 634, such as a serial (e.g.,universal serial bus (USB), parallel, or other wired or wireless (e.g.,infrared (IR), near field communication (NFC), etc.) connection tocommunicate with or control one or more peripheral devices (e.g., aprinter, a card reader, etc.)).

The storage device 616 may include a machine readable medium 622 onwhich is stored one or more sets of data structures or instructions 624(e.g., software) embodying or utilized by any one or more of thetechniques or functions described herein. The instructions 624 may alsoreside, completely or at least partially, within the main memory 604,within the static memory 606, or within the hardware processor 602during execution thereof by the machine 600. In an example, one or anycombination of the hardware processor 602, the main memory 604, thestatic memory 606, or the storage device 616 may constitutemachine-readable media.

The restrictive TWT SP device 619 may carry out or perform any of theoperations and processes (e.g., the processes 400 and 450) described andshown above. For example, the restrictive TWT SP device 619 may beconfigured to limit the allocation and transmission of trigger frameswithin a TWT SP in order to minimize collisions between uplink (UL)frames or other frames within a TWT SP.

The restrictive TWT SP device 619 may prohibit an AP from scheduling atrigger frame transmission close to the end of a TWT SP.

The restrictive TWT SP device 619 may set a cascade indication fieldwithin a trigger frame to be sent to one or more PS devices based atleast in part on one or more conditions.

The restrictive TWT SP device 619 may determine the one or moreconditions associated with the duration of the TWT SP such that thetrigger frame is sent to the one or more PS devices when the one or moreconditions are met. The one or more conditions may be associated withdetermining a remaining duration of the TWT SP and comparing that to oneor more durations associated with, at least in part, the trigger frame,one or more interframe space durations, one or more UL frame durations,and/or one or more acknowledgment durations.

The restrictive TWT SP device 619 may determine a last trigger frame tobe sent to one or more PS devices based at least in part on the cascadeindication field being sent to a predetermined value. For example, theAP may set the cascade indication field to 0 in the last trigger framewithin the TWT SP.

The restrictive TWT SP device 619 may determine an acknowledgment policybit associated with the QoS field of an uplink frame. For example, ifthe acknowledgment policy bit is set to 1, this may indicate that the APmay receive an acknowledgment from the one or more PS devices. However,if the acknowledgment policy bit is set to 0, this may indicate that theAP will not be receiving an acknowledgment from the one or more PSdevices.

The restrictive TWT SP device 619 may ignore the acknowledgment policybit based at least in part on the type of communication between the APand the one or more PS devices.

It is understood that the above actions are only a subset of what therestrictive TWT SP device 619 may be configured to perform and thatother functions included throughout this disclosure may also beperformed by the restrictive TWT SP device 619.

While the machine-readable medium 622 is illustrated as a single medium,the term “machine-readable medium” may include a single medium ormultiple media (e.g., a centralized or distributed database, and/orassociated caches and servers) configured to store the one or moreinstructions 624.

Various embodiments may be implemented fully or partially in softwareand/or firmware. This software and/or firmware may take the form ofinstructions contained in or on a non-transitory computer-readablestorage medium. Those instructions may then be read and executed by oneor more processors to enable performance of the operations describedherein. The instructions may be in any suitable form, such as but notlimited to source code, compiled code, interpreted code, executablecode, static code, dynamic code, and the like. Such a computer-readablemedium may include any tangible non-transitory medium for storinginformation in a form readable by one or more computers, such as but notlimited to read only memory (ROM); random access memory (RAM); magneticdisk storage media; optical storage media; a flash memory, etc.

The term “machine-readable medium” may include any medium that iscapable of storing, encoding, or carrying instructions for execution bythe machine 600 and that cause the machine 600 to perform any one ormore of the techniques of the present disclosure, or that is capable ofstoring, encoding, or carrying data structures used by or associatedwith such instructions. Non-limiting machine-readable medium examplesmay include solid-state memories and optical and magnetic media. In anexample, a massed machine-readable medium includes a machine-readablemedium with a plurality of particles having resting mass. Specificexamples of massed machine-readable media may include non-volatilememory, such as semiconductor memory devices (e.g., electricallyprogrammable read-only memory (EPROM), or electrically erasableprogrammable read-only memory (EEPROM)) and flash memory devices;magnetic disks, such as internal hard disks and removable disks;magneto-optical disks; and CD-ROM and DVD-ROM disks.

The instructions 624 may further be transmitted or received over acommunications network 626 using a transmission medium via the networkinterface device/transceiver 620 utilizing any one of a number oftransfer protocols (e.g., frame relay, internet protocol (IP),transmission control protocol (TCP), user datagram protocol (UDP),hypertext transfer protocol (HTTP), etc.). Example communicationsnetworks may include a local area network (LAN), a wide area network(WAN), a packet data network (e.g., the Internet), mobile telephonenetworks (e.g., cellular networks), plain old telephone (POTS) networks,wireless data networks (e.g., Institute of Electrical and ElectronicsEngineers (IEEE) 802.11 family of standards known as Wi-Fi®, IEEE 802.16family of standards known as WiMax®), IEEE 802.15.4 family of standards,and peer-to-peer (P2P) networks, among others. In an example, thenetwork interface device/transceiver 620 may include one or morephysical jacks (e.g., Ethernet, coaxial, or phone jacks) or one or moreantennas to connect to the communications network 626. In an example,the network interface device/transceiver 620 may include a plurality ofantennas to wirelessly communicate using at least one of single-inputmultiple-output (SIMO), multiple-input multiple-output (MIMO), ormultiple-input single-output (MISO) techniques. The term “transmissionmedium” shall be taken to include any intangible medium that is capableof storing, encoding, or carrying instructions for execution by themachine 600 and includes digital or analog communications signals orother intangible media to facilitate communication of such software. Theoperations and processes described and shown above may be carried out orperformed in any suitable order as desired in various implementations.Additionally, in certain implementations, at least a portion of theoperations may be carried out in parallel. Furthermore, in certainimplementations, less than or more than the operations described may beperformed.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. The terms “computing device,” “userdevice,” “communication station,” “station,” “handheld device,” “mobiledevice,” “wireless device” and “user equipment” (UE) as used hereinrefers to a wireless communication device such as a cellular telephone,a smartphone, a tablet, a netbook, a wireless terminal, a laptopcomputer, a femtocell, a high data rate (HDR) subscriber station, anaccess point, a printer, a point of sale device, an access terminal, orother personal communication system (PCS) device. The device may beeither mobile or stationary.

As used within this document, the term “communicate” is intended toinclude transmitting, or receiving, or both transmitting and receiving.This may be particularly useful in claims when describing theorganization of data that is being transmitted by one device andreceived by another, but only the functionality of one of those devicesis required to infringe the claim. Similarly, the bidirectional exchangeof data between two devices (both devices transmit and receive duringthe exchange) may be described as “communicating,” when only thefunctionality of one of those devices is being claimed. The term“communicating” as used herein with respect to a wireless communicationsignal includes transmitting the wireless communication signal and/orreceiving the wireless communication signal. For example, a wirelesscommunication unit, which is capable of communicating a wirelesscommunication signal, may include a wireless transmitter to transmit thewireless communication signal to at least one other wirelesscommunication unit, and/or a wireless communication receiver to receivethe wireless communication signal from at least one other wirelesscommunication unit.

As used herein, unless otherwise specified, the use of the ordinaladjectives “first,” “second,” “third,” etc., to describe a commonobject, merely indicates that different instances of like objects arebeing referred to and are not intended to imply that the objects sodescribed must be in a given sequence, either temporally, spatially, inranking, or in any other manner.

The term “access point” (AP) as used herein may be a fixed station. Anaccess point may also be referred to as an access node, a base station,or some other similar terminology known in the art. An access terminalmay also be called a mobile station, user equipment (UE), a wirelesscommunication device, or some other similar terminology known in theart. Embodiments disclosed herein generally pertain to wirelessnetworks. Some embodiments may relate to wireless networks that operatein accordance with one of the IEEE 802.11 standards.

Some embodiments may be used in conjunction with various devices andsystems, for example, a personal computer (PC), a desktop computer, amobile computer, a laptop computer, a notebook computer, a tabletcomputer, a server computer, a handheld computer, a handheld device, apersonal digital assistant (PDA) device, a handheld PDA device, anon-board device, an off-board device, a hybrid device, a vehiculardevice, a non-vehicular device, a mobile or portable device, a consumerdevice, a non-mobile or non-portable device, a wireless communicationstation, a wireless communication device, a wireless access point (AP),a wired or wireless router, a wired or wireless modem, a video device,an audio device, an audio-video (A/V) device, a wired or wirelessnetwork, a wireless area network, a wireless video area network (WVAN),a local area network (LAN), a wireless LAN (WLAN), a personal areanetwork (PAN), a wireless PAN (WPAN), and the like.

Some embodiments may be used in conjunction with one way and/or two-wayradio communication systems, cellular radio-telephone communicationsystems, a mobile phone, a cellular telephone, a wireless telephone, apersonal communication system (PCS) device, a PDA device whichincorporates a wireless communication device, a mobile or portableglobal positioning system (GPS) device, a device which incorporates aGPS receiver or transceiver or chip, a device which incorporates an RFIDelement or chip, a multiple input multiple output (MIMO) transceiver ordevice, a single input multiple output (SIMO) transceiver or device, amultiple input single output (MISO) transceiver or device, a devicehaving one or more internal antennas and/or external antennas, digitalvideo broadcast (DVB) devices or systems, multi-standard radio devicesor systems, a wired or wireless handheld device, e.g., a smartphone, awireless application protocol (WAP) device, or the like.

Some embodiments may be used in conjunction with one or more types ofwireless communication signals and/or systems following one or morewireless communication protocols, for example, radio frequency (RF),infrared (IR), frequency-division multiplexing (FDM), orthogonal FDM(OFDM), time-division multiplexing (TDM), time-division multiple access(TDMA), extended TDMA (E-TDMA), general packet radio service (GPRS),extended GPRS, code-division multiple access (CDMA), wideband CDMA(WCDMA), CDMA 2000, single-carrier CDMA, multi-carrier CDMA,multi-carrier modulation (MDM), discrete multi-tone (DMT), Bluetooth®,global positioning system (GPS), Wi-Fi, Wi-Max, ZigBee, ultra-wideband(UWB), global system for mobile communications (GSM), 2G, 2.5G, 3G,3.5G, 4G, fifth generation (5G) mobile networks, 3GPP, long termevolution (LTE), LTE advanced, enhanced data rates for GSM Evolution(EDGE), or the like. Other embodiments may be used in various otherdevices, systems, and/or networks.

According to example embodiments of the disclosure, there may be adevice. The device may include at least one memory that storescomputer-executable instructions; and at least one processor configuredto access the at least one memory, wherein the at least one processor isconfigured to execute the computer-executable instructions to: determinea beacon frame to be sent to one or more power save devices; determine atime duration of a target wake time (TWT) service period (SP) associatedwith the one or more power save devices; determine a first trigger frameincluding a cascade indication; determine a first time associated withthe first trigger frame; and cause to send the trigger frame to the oneor more power save devices based at least in part on a remainingduration of the TWT SP.

The implementations may include one or more of the following features.The cascade indication is set to 1 to indicate an additional triggerframe transmission within the TWT SP. The cascade indication is set to 0to indicate a last trigger frame transmission within the TWT SP. The atleast one processor may be further configured to execute thecomputer-executable instructions to: determine an acknowledgment policyassociated with a quality of service (QoS) field of the UL PPDU is setto a first value indicating an immediate acknowledgment; set the cascadeindication to 1 when the remaining duration is greater than or equal toa sum of two or more of a trigger frame duration, a short interfamespace (SIFS) duration, an uplink (UL) MU Physical Layer ConvergenceProtocol PLCP Protocol Data Unit (PPDU) duration, an additional SIFSduration, and an acknowledgment duration; and set the cascade indicationto 0 when the remaining duration is less than the sum. The at least oneprocessor may be further configured to execute the computer-executableinstructions to: determine an acknowledgment policy associated with aquality of service (QoS) field of the UL PPDU is set to a second value;set the cascade indication to 1 when the remaining duration of the TWTSP is greater than or equal to a sum of a cascaded trigger frameduration, a short interfame space (SIFS) duration, and an uplink (UL)multi-user (MU) Physical Layer Convergence Protocol PLCP Protocol DataUnit (PPDU) duration; and set the cascade indication to 0 when theremaining duration of the TWT SP is less than the sum. The first timeassociated with the first trigger frame is a time when the first triggerframe is to be sent to at least one of the one or more power savedevices. The remaining duration of the TWT SP is a difference between aTWT SP end time and an end time associated with an end of an uplink ordownlink multi-user operation solicited by the first trigger frame. Thefirst trigger frame is at least one of a cascaded trigger frame or anon-cascaded trigger frame. The acknowledgment duration is at least oneof a device acknowledgment (ACK) duration, a block acknowledgment (BA)duration, or a multi-device block acknowledgment (MBA) duration. Thedevice may further include a transceiver configured to transmit andreceive wireless signals. The device may further include at least oneantenna coupled to the transceiver.

According to example embodiments of the disclosure, there may be anon-transitory computer-readable medium storing computer-executableinstructions which, when executed by a processor, cause the processor toperform operations. The operations may include identifying a beaconreceived from a first device; determining a target wake time (TWT)service period (SP); and identifying a trigger frame including a cascadeindication based at least in part on a remaining duration of the TWT SP.

The implementations may include one or more of the following features.The cascade indication is set to 1 to indicate an additional triggerframe transmission within the TWT SP. The cascade indication is set to 0to indicate a last trigger frame transmission within the TWT SP. Theremaining duration of the TWT SP is a difference between an end time ofthe TWT SP and a first time when the trigger frame is to be sent by thefirst device. The trigger frame is at least one of a cascaded triggerframe or a non-cascaded trigger frame. The remaining duration of the TWTSP is greater than or equal to a sum of two or more of a trigger frameduration, a short interframe space (SIFS) duration, an uplink (UL)physical layer convergence protocol PLCP protocol data unit (PPDU)duration, and an acknowledgment duration, when an acknowledgment policyassociated with a quality of service (QoS) field of the UL PPDU is setto 1. The acknowledgment duration is at least one of a deviceacknowledgment (ACK) duration, a block acknowledgment (BA) duration, ora multi-device block acknowledgment (MBA) duration.

According to example embodiments of the disclosure, there may include amethod. The method may include determining a beacon frame to be sent toone or more power save devices; determining a time duration of a targetwake time (TWT) service period (SP) associated with the one or morepower save devices; determining a first trigger frame including acascade indication; determining a first time associated with the firsttrigger frame; and causing to send the trigger frame to the one or morepower save devices based at least in part on a remaining duration of theTWT SP.

The implementations may include one or more of the following features.The cascade indication is set to 1 to indicate an additional triggerframe transmission within the TWT SP. The cascade indication is set to 0to indicate a last trigger frame transmission within the TWT SP. Themethod may further include determining an acknowledgment policyassociated with a quality of service (QoS) field of the UL PPDU is setto a first value indicating an immediate acknowledgment; setting thecascade indication to 1 when the remaining duration is greater than orequal to a sum of two or more of a trigger frame duration, a shortinterfame space (SIFS) duration, an uplink (UL) MU Physical LayerConvergence Protocol PLCP Protocol Data Unit (PPDU) duration, the SIFSduration, and an acknowledgment duration; and setting the cascadeindication to 0 when the remaining duration is less than the sum. Themethod may further include: determining an acknowledgment policyassociated with a quality of service (QoS) field of the UL PPDU is setto a second value; setting the cascade indication to 1 when theremaining duration of the TWT SP is greater than or equal to a sum of acascaded trigger frame duration, a short interfame space (SIFS)duration, and an uplink (UL) multi-user (MU) Physical Layer ConvergenceProtocol PLCP Protocol Data Unit (PPDU) duration; and setting thecascade indication to 0 when the remaining duration of the TWT SP isless than the sum. The first time associated with the first triggerframe is a time when the first trigger frame is to be sent to at leastone of the one or more power save devices. The remaining duration of theTWT SP is a difference between a TWT SP end time and an end timeassociated with an end of an uplink or downlink multi-user operationsolicited by the first trigger frame. The first trigger frame is atleast one of a cascaded trigger frame or a non-cascaded trigger frame.The acknowledgment duration is at least one of a device acknowledgment(ACK) duration, a block acknowledgment (BA) duration, or a multi-deviceblock acknowledgment (MBA) duration.

In example embodiments of the disclosure, there may be an apparatus. Theapparatus may include means for determining a beacon frame to be sent toone or more power save devices. The apparatus may include means fordetermining a time duration of a target wake time (TWT) service period(SP) associated with the one or more power save devices. The apparatusmay include means for determining a first trigger frame including acascade indication. The apparatus may include means for determining afirst time associated with the first trigger frame. The apparatus mayinclude means for causing to send the trigger frame to the one or morepower save devices based at least in part on a remaining duration of theTWT SP.

The implementations may include one or more of the following features.The cascade indication is set to 1 to indicate an additional triggerframe transmission within the TWT SP. The cascade indication is set to 0to indicate a last trigger frame transmission within the TWT SP. Theapparatus may further include: means for determining an acknowledgmentpolicy associated with a quality of service (QoS) field of the UL PPDUis set to a first value indicating an immediate acknowledgment; meansfor setting the cascade indication to 1 when the remaining duration isgreater than or equal to a sum of two or more of a trigger frameduration, a short interfame space (SIFS) duration, an uplink (UL) MUPhysical Layer Convergence Protocol PLCP Protocol Data Unit (PPDU)duration, the SIFS duration, and an acknowledgment duration; and meansfor setting the cascade indication to 0 when the remaining duration isless than the sum. The apparatus may further comprise: means fordetermining an acknowledgment policy associated with a quality ofservice (QoS) field of the UL PPDU is set to a second value; means forsetting the cascade indication to 1 when the remaining duration of theTWT SP is greater than or equal to a sum of a cascaded trigger frameduration, a short interfame space (SIFS) duration, and an uplink (UL)multi-user (MU) Physical Layer Convergence Protocol PLCP Protocol DataUnit (PPDU) duration; and means for setting the cascade indication to 0when the remaining duration of the TWT SP is less than the sum. Thefirst time associated with the first trigger frame is a time when thefirst trigger frame is to be sent to at least one of the one or morepower save devices. The remaining duration of the TWT SP is a differencebetween a TWT SP end time and an end time associated with an end of anuplink or downlink multi-user operation solicited by the first triggerframe. The first trigger frame is at least one of a cascaded triggerframe or a non-cascaded trigger frame. The acknowledgment duration is atleast one of a device acknowledgment (ACK) duration, a blockacknowledgment (BA) duration, or a multi-device block acknowledgment(MBA) duration.

Certain aspects of the disclosure are described above with reference toblock and flow diagrams of systems, methods, apparatuses, and/orcomputer program products according to various implementations. It willbe understood that one or more blocks of the block diagrams and flowdiagrams, and combinations of blocks in the block diagrams and the flowdiagrams, respectively, may be implemented by computer-executableprogram instructions. Likewise, some blocks of the block diagrams andflow diagrams may not necessarily need to be performed in the orderpresented, or may not necessarily need to be performed at all, accordingto some implementations.

These computer-executable program instructions may be loaded onto aspecial-purpose computer or other particular machine, a processor, orother programmable data processing apparatus to produce a particularmachine, such that the instructions that execute on the computer,processor, or other programmable data processing apparatus create meansfor implementing one or more functions specified in the flow diagramblock or blocks. These computer program instructions may also be storedin a computer-readable storage media or memory that may direct acomputer or other programmable data processing apparatus to function ina particular manner, such that the instructions stored in thecomputer-readable storage media produce an article of manufactureincluding instruction means that implement one or more functionsspecified in the flow diagram block or blocks. As an example, certainimplementations may provide for a computer program product, comprising acomputer-readable storage medium having a computer-readable program codeor program instructions implemented therein, said computer-readableprogram code adapted to be executed to implement one or more functionsspecified in the flow diagram block or blocks. The computer programinstructions may also be loaded onto a computer or other programmabledata processing apparatus to cause a series of operational elements orsteps to be performed on the computer or other programmable apparatus toproduce a computer-implemented process such that the instructions thatexecute on the computer or other programmable apparatus provide elementsor steps for implementing the functions specified in the flow diagramblock or blocks.

Accordingly, blocks of the block diagrams and flow diagrams supportcombinations of means for performing the specified functions,combinations of elements or steps for performing the specified functionsand program instruction means for performing the specified functions. Itwill also be understood that each block of the block diagrams and flowdiagrams, and combinations of blocks in the block diagrams and flowdiagrams, may be implemented by special-purpose, hardware-based computersystems that perform the specified functions, elements or steps, orcombinations of special-purpose hardware and computer instructions.

Conditional language, such as, among others, “can,” “could,” “might,” or“may,” unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainimplementations could include, while other implementations do notinclude, certain features, elements, and/or operations. Thus, suchconditional language is not generally intended to imply that features,elements, and/or operations are in any way required for one or moreimplementations or that one or more implementations necessarily includelogic for deciding, with or without user input or prompting, whetherthese features, elements, and/or operations are included or are to beperformed in any particular implementation.

Many modifications and other implementations of the disclosure set forthherein will be apparent having the benefit of the teachings presented inthe foregoing descriptions and the associated drawings. Therefore, it isto be understood that the disclosure is not to be limited to thespecific implementations disclosed and that modifications and otherimplementations are intended to be included within the scope of theappended claims. Although specific terms are employed herein, they areused in a generic and descriptive sense only and not for purposes oflimitation.

What is claimed is:
 1. A device for scheduling target wake times forstation devices, the device comprising processing circuitry coupled tostorage, the processing circuitry configured to: determine a target waketime of a target wake time service period for a station device, whereinthe target wake time occurs after a first beacon sent by the device andbefore a second beacon sent by the device, wherein the first beacon andthe second beacons are consecutive beacons, wherein the target wake timeoccurs after the station device receives the first beacon and after thestation device enters a first doze state after receiving the firstbeacon, and wherein the first doze state ends before the station deviceenters a second doze state before waking up and receiving the secondbeacon from the device; cause to send the first beacon to one or morestation devices, the first beacon comprising an indication of the targetwake time; and cause to send one or more trigger frames during thetarget wake time service period.
 2. The device of claim 1, wherein thefirst doze state occurs between a first trigger frame and a secondtrigger frame of the one or more trigger frames.
 3. The device of claim1, wherein the target wake time service period is periodic.
 4. Thedevice of claim 1, wherein the one or more trigger frames comprise afirst trigger frame, and wherein the first trigger frame comprises anindication that the first trigger frame is the last trigger frame of thetarget wake time service period.
 5. The device of claim 1, wherein theprocessing circuitry is further configured to identify a poll receivedfrom a station device of the one or more station devices before sendingthe one or more trigger frames, wherein the poll indicates that thestation device is awake from the first doze state that began after thefirst beacon.
 6. The device of claim 1, further comprising a transceiverconfigured to transmit and receive wireless signals, wherein thewireless signals comprise at least one of the first beacon or the one ormore trigger frames.
 7. The device of claim 6, further comprising atleast one antenna coupled to the transceiver.
 8. A non-transitorycomputer-readable medium storing computer-executable instructions whichwhen executed by one or more processors result in performing operationscomprising: identifying, at a first device, a first beacon received froma second device, the first beacon comprising an indication of a targetwake time that occurs after the first device enters a first doze stateafter receiving the first beacon, and ends before the first deviceenters a second doze state before receiving a second beacon from thesecond device, wherein the first beacon and the second beacon areconsecutive beacons; determining that the first device is to wake fromthe first doze state based on the target wake time; causing the firstdevice to enter the first doze state after receiving the first beacon;causing the first device to wake from the first doze state at the targetwake time; identifying one or more trigger frames received from thesecond device; causing the first device to enter the second doze stateafter receiving the one or more trigger frames; causing the first deviceto wake from the second doze state; and identifying the second beaconreceived from the second device.
 9. The non-transitory computer-readablemedium of claim 8, the operations further comprising determining thatthe target wake time service period is periodic.
 10. The non-transitorycomputer-readable medium of claim 8, the operations further comprisingdetermining that the target wake time service period is aperiodic. 11.The non-transitory computer-readable medium of claim 8, wherein the oneor more trigger frames comprise a first trigger frame, and wherein thefirst trigger frame comprises an indication that the first trigger frameis the last trigger frame of the target wake time service period. 12.The non-transitory computer-readable medium of claim 8, the operationsfurther comprising causing to send a poll indicates that the firstdevice is awake during the target wake time service period.
 13. A methodcomprising: determining, by an access point, a target wake time of atarget wake time service period for a station device, wherein the targetwake time occurs after a first beacon sent by the access point andbefore a second beacon sent by the access point, wherein the firstbeacon and the second beacons are consecutive beacons, wherein thetarget wake time occurs after the station device receives the firstbeacon and after the station device enters a first doze state afterreceiving the first beacon, and wherein the first doze state ends beforethe station device enters a second doze state before waking up andreceiving the second beacon from the access point; causing to send thefirst beacon to one or more station devices, the first beacon comprisingan indication of the target wake time; and causing to send one or moretrigger frames during the target wake time service period.
 14. Themethod of claim 13, wherein the first doze state occurs between a firsttrigger frame and a second trigger frame of the one or more triggerframes.
 15. The method of claim 13, wherein the target wake time serviceperiod is periodic.
 16. The method of claim 13, wherein the one or moretrigger frames comprise a first trigger frame, and wherein the firsttrigger frame comprises an indication that the first trigger frame isthe last trigger frame of the target wake time service period.
 17. Themethod of claim 13, further comprising identifying a poll received froma station device of the one or more station devices, wherein the pollindicates that the station device is awake during the target wake timeservice period.